Abstract Hexavalent chromium ion (Cr6+) is highly toxic to human health and environment. Herein, high-performance detection of Cr6+ is of great import. In this study, a rapid and sensitive multicolor colorimetric method for detection of Cr6+ in aqueous solution was established on the basis of Cr6+ etching of gold nano-double cone@silver nanorods (Au NDC@Ag NRs). Au NDC@Ag NRs was synthesized by a modified seed-mediated growth method. The catalytic etching induced by Cr6+ changed the morphology of Au NDC@Ag NRs, leading to the attenuation of surface plasma resonance (SPR) and the redshift of absorption spectra. Meanwhile, Au NDC@Ag NRs exhibits obvious color changes from orange to pink, to purple, and finally becomes colorless with the increasing concentrations of Cr6+. With such a design, naked-eye detection of Cr6+ was realized with high sensitivity. The proposed multicolor sensing method showed a good linearity between the redshift change of absorption peak (△λ) and the concentrations of Cr6+ in the range from 2.5 to 40 μM. The limit of detection (LOD) was calculated as 1.69 μM in aqueous solution. In addition, successful detection of Cr6+ in tap water and Yangtze River water, indicating the real applications of Au NDC@Ag NRs probe in monitoring Cr6+ in environment.

中文翻译：

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使用金纳米双锥@银纳米棒的催化蚀刻基于表面等离子体共振比色检测Cr6+离子

摘要 六价铬离子（Cr6+）对人体健康和环境具有剧毒。在此，Cr6+ 的高性能检测具有重要意义。本研究以金纳米双锥@银纳米棒（Au NDC@Ag NRs）的Cr6+蚀刻为基础，建立了一种快速灵敏的多色比色法检测水溶液中的Cr6+。Au NDC@Ag NRs 是通过改良的种子介导生长方法合成的。Cr6+引起的催化蚀刻改变了Au NDC@Ag NRs的形貌，导致表面等离子体共振（SPR）衰减和吸收光谱红移。同时，随着 Cr6+ 浓度的增加，Au NDC@Ag NRs 表现出明显的颜色变化，从橙色到粉红色，再到紫色，最后变为无色。有了这样的设计，实现了高灵敏度的 Cr6+ 肉眼检测。所提出的多色传感方法在 2.5 至 40 μM 范围内的吸收峰红移变化 (△λ) 与 Cr6+ 浓度之间显示出良好的线性关系。检测限 (LOD) 在水溶液中计算为 1.69 μM。此外，在自来水和长江水中成功检测到Cr6+，表明Au NDC@Ag NRs探针在环境中Cr6+监测中的真正应用。